The accumulation of ice on aircraft wings and other structural members in flight is a danger that is well known. As used herein, the term structural member is intended to refer to any aircraft surface susceptible to icing, including wings and so forth. Attempts have been made since the earliest days of flight to overcome the problem of ice accumulation. A variety of techniques have been proposed for removing ice from aircraft during flight. A common problem, however, is the accumulation of ice on structural members while the aircraft is sitting on the ground. Once such condition is known as clear ice. Clear ice may form on exposed wing or other surfaces at temperatures well above freezing due to rain or humidity condensation. This ice formation occurs when fuel within wing fuel tanks has been cold soaked to below freezing, resulting in the wing surface temperature being below freezing until the fuel has warmed. Accumulations of clear ice up to one inch thick have been experienced due to this type of icing. Attempts to take off with the accumulation of clear ice on the wings can lead to disastrous results of foreign object damage (FOD) to fuselage rear mounted engines. The clear ice layer breaks free from the wings during rotation and is ingested by the engines, causing loss of power thereof.
Efforts to eliminate clear ice formation and to improve the safety have led to continuing developments to improve versatility, practicality and efficiency.